1. Field of the Invention
This invention relates to an optical pickup for reading out information from an information recorded media, such as an optical diskette, and more particularly, to an optical pickup not including a conventional glass lens, but including light and compact-sized hologram lens.
2. Description of the Related Art
An optical pickup P, known in the prior art, includes, as seen from FIG. 24, an optical system comprising a semiconductor laser source 1, a collimator lens 2, a prism pair 3, a prism splitter 4, a (1/4.multidot..lambda.) wave plate 5, an objective lens 6, a focussing lens 7, and an optical sensor 8, and these elements constitute a single unit. As seen from FIG. 25, the access to the above-mentioned conventional optical pickup is carried out by a linear motor LM with respect to an optical diskette D which is rotated by a motor M.
However, according to the conventional optical pickup, the principal elements constituting the optical system are made of glass or the like. Therefore, in order to ensure a required quality or capacity, the system is necessarily heavy and large in size. In a typical example, the pickup is at least several deca grams in weight, even if efforts have been made to reduce the weight thereof.
Therefore, a light and compact-sized pickup has long been desired in this field of the art, since it is very important to reduce the access time to an information storage media, such as an optical diskette capable of storing large quantities of information, and the access time depends on the speed of pickup when moved by the above-mentioned linear motor LM, which speed in turn depends largely on the weight of the pickup.